The present invention relates to a screw-and-nut mechanism with ball or roller recirculation.
Mechanisms of this kind are used for transforming a rotational movement into a translatory movement, and for effecting such transformation in the reverse order; these devices each comprise a screw and a nut having one or more screw-threads disposed in such a way as to delimit one or more running channels for balls or rollers between the end faces of the nut, thereby ensuring transmission of the forces with very little friction and enabling such transformation of movement to be effected with a very high efficiency. When the balls or rollers have reached one end of the circulating channel they have to be led back to the other end of the same channel in such a way as to run in a closed circuit. Various methods are known for effecting this "recirculation" of the balls or rollers, particularly via a recirculating channel which is disposed externally with respect to the screw-thread of the nut, so as to connect the two ends of the circulating channel.
Various embodiments of such recirculating channels are known, which include merely a duct machined into the material of the nut externally with respect to its threading, or a tubular element in one piece or in two half-shells, or including one or more connecting means which may likewise be composed of half-shells.
These various elements are formed, for instance in sheet metal, in drawn sheet metal, in cast steel or in molded synthetic material. Each element thus acts in such a way that all or part of the recirculating device may appear in different embodiments as regards either the particular geometrical design, the material used, the mode of connection to the nut member or to one of the other recirculating elements.